Isotopic Composition of Water Used in Triple-Point Cells

Isotopic analysis of the water used in KRISS triple point of water (TPW) cells was performed by three separate laboratories. The δD and δ ¹⁸O isotopic composition of six ampoules, made from two TPW cells, were analyzed by isotope ratio mass spectrometers. The analysis data showed that δD and δ ¹⁸O were − 62.17‰ and − 9.41‰ for the KRISS-2002-Jan cell, and − 36.42‰ and − 4.08‰ for the KRISS-2005-Jun cell. The temperature deviation of the triple point of water for these cells calculated from Kiyosawa’s data and the definition of the TPW were + 45.07μK for the KRISS-2002-Jan cell, and + 25.49μK for the KRISS-2005-Jun cell. The KRISS TPW temperature was + 92μK higher than the CCT-K7 KCRV after correcting for the deviation of the isotopic composition from Vienna Standard Mean Ocean Water.